Electrical computing device



March 21, 1950 T. D. MORGAN 2,500,997

ELECTRICAL COMPUTING DEVICE Filed July 13, 1944 INVENTOR THOMAS o.MORGAN ATTORNEY Patented Mar. 21, 1950 PATENT rice ELECTRICAL CQMPUTINGDEVICE of Delaware Application July 13,

2 Shims.-

The present invention relates to a device for solving systems ofsimultaneous linear equations which are solvable by the well knownmethod of iteration or successive approximations. Such systems ofequations which are capable of practical solution by this method will beherein termed convergent systems of simultaneous equations.

Although the device may be utilized in solving any convergent system ofn linear simultaneous equations of the type above mentioned it will bedescribed in connection with the determination of percentages of thevarious constituents of a hydrocarbon mixture. Recently, infraredspectrophotometry has been used for the purpose of analyzinghydrocarbons, as is described in some detail in National Petroleum Newsfor May 3, 1944, section 2, at page R274. Such analysis of hydrocarbonsby means of infrared spectrophotometry ofiers many advantages over otheranalysis methods but requires a large amount of computation which thepresent invention eliminates. In analyzing petroleum hydrocarbons todetermine the percentages of the constituents of a mixture the infraredspectrophotometer is utilized in the following manner, it being assumedthat the analyst knows the wave lengths at which each constituent of themixture has as large an extinction coefficient as possible when comparedwith the extinction coefiicients of the other constituents. The analystthen, by the use of the spectrophotometer, determine the totalextinction produced by a sample of the mixture at each of the selectedwave lengths, there being, of course, one wave length for each mixtureconstituent. For example, if a four component mixture be considered theprocedure will be to first analyze a sample of this mixture at a wavelength L1, this wave length being chosen to cause as great an extinctionas possible with respect to the first component of the mixture ascompared with the extinction caused by the remaining components thereof.In a similar manner, a second extinction value will be determined forthe sample at a wave length L2 chosen to cause as great an extinction aspossible due to the second component of the mixture as compared with theremaining components. In a similar manner, readings will be taken atwave lengths L3 and L4. Then, since the total extinction brought aboutby the mixture at any wave length must be 1944, Serial No. 5%,745

equal to the sum of the extinctions brought about by each of thecomponents of the mixture a set of equations may be written as follows:

In these equations w, r, y, and a are the percents 1c of the componentsof the mixture; A1, A2, A3 and A4 are the extinction coefilcients forcomponent w at wave lengths L1, L2, L3 and L4 respectively; B1, B2, B3and B4 are the extinction coefficients for component :6 at wave lengthsL1, L2, L3 and L4 respectively; C1, C2, C3 and C4 are the extinctioncoemcients for component y at Wave lengths L1, L2, L3 and L4; D1, D2, D3and D4 are the extinction coefficients for component a at wave lengthsL1, L2, L3 and L4 respectively; and K1, K2, K3 and K4 are the totalextinction coefficients at wave lengths L1, L2, L3 and L4 respectively.

As has been stated, equations of this type may be solved by the methodof systematically making successive approximations of the percentage ofeach component so that the approximations approach the correct solutionto the problem and repeating the approximations until the differencebetween successive approximations becomes less than the experimentalerror of the original data,

at which time an answer will be at hand which is consistent in accuracywith the accuracy of the experimental data. However, this methodrequires a very considerable knowledge of mathematical procedure andconsiderable time. Further, even when reduced to a routine procedure thetime element is still large and a knowledge of the effect of startingwith a particular approximation is required in order to reduce the timeto the minimum possible.

0 The present invention provides electrical circuits includingpotentiometers which are adjusted in accordance with the experimentaldata and through which the results may be read directly in a minimum oftime.

It is an object of this invention to provide electrical means forsolving simultaneous equations. It is another object of the invention toprovide a device for solving such simultaneous equations resulting fromthe infrared spectrophotometer 0 analysis of petroleum hydrocarbons.

It is a further object of the invention to provide such an electricalcomputer which shall be simple in construction and easy to operate.

Other objects and features of the invention will appear when thefollowing description is considered in connection with the annexeddrawing, in which:

Figure 1 is a schematic wiring diagram of my invention; and

Figure 2 is a schematic circuit diagram showing the manner in whichreversing switches are utilized to insert negative coeflicients.

Referring now to the drawing it will be seen that there are provided aplurality of potentiometers K1, K2, K3 and K4 which potentiometers areto be set in accordance with the readings of total extinction asmentioned hereinabove. It will be noted that each of thesepotentiometers is in a circuit which passes through additionalpotentiometers and may be closed through a galvanometer ill.

Thus, the circuit extending from potentiometer K1 proceeds from itsadjustable contact to a potentiometer A1 and thence throughpotentiommeter m1 and its adjustable contact to potentiometer B1; thencethrough adjustable contact of potentiometer B1 to potentiometer x1through its adjustable contact to potentiometer C1, thencethrough itscontact to potentiometer yi, thence to potentiometer D1, potentiometer21 and to the galvanometer it through the variable resistance H.

The circuits for potentiometers K2, K3 and K4 are similar to the onejust above described and lead also to the galvanometer through thevariable resistance li. Each of the potentiometers K1, &, K3 and K4 hasin circuit therewith a battery respectively designated !2, l3, l4 and i5and each of the potentiometers A1 through D4 has in its circuit abattery, the latter batteries (16 in number) being poled oppositely tothe batteries 82, 33, i4 and 15. Further, each galvanometer circuit hasin series therewith a switch respectively designated Ni, ii, l8 and i9,these switches being used to close the separate circuits through thegalvanometer, one at a time in an order which will be describedhereinafter. It should be noted that the potentiometers wi, wz, we and1124 have their movable contacts mechanically interconnected and thatthese contacts are operated by a handle 20 which cooperates with a scaleto indicate its setting. In like manner, the potentiometers x1, :22, 1:3and :04 are mechanically interconnected and connected to an adjustingknob or handle and likewise the y potentiometers and the epotentiometers respectively are interconnected and are connected tooperating handles y and 2. Further, the potentiometers A1, A2, A: and A4D4 are provided with scales (not shown) so that their position may beadjusted.

In using the computer the potentiometer K1 is set to a position suchthat its scale indicates the measured extinction at wave length L1,potentiometer K2 is set so that its scale indicates the measuredextinction at wave length L2 potentiometer K3 is set so that its scaleindicates the measured extinction at wave length L3 and potentiometer K4is set so that its scale indicates proportionately to the measuredextinction at wave length L4.

Also potentiometers A1 through D1 are set to indications proportional tothe extinctions brought about by pure substances w, :c, y and arespectively at wave length L1, potentiometers A2 through D2 are set toindications proportional to the extinctions brought about by puresubstances w, x, y and 2 respectively at wave length L2, potentiometersA3 through D3 are set to indications proportional to the extinctionsbrought about by pure substances w, m, y and 2 respectively at wavelength L3, and potentiometers A4 through D4.- are set to indicationsproportional to the extinctions brought about by pure substances w, m, yand 2 respectively at wave length L4.

Switch IE is now closed thereby completing a circuit throughpotentiometers K1, 101, B1, x1 C1, n, D1, 21, rheostate II andgalvanometer Hi. Adjusting knob or handle 11; is then operated until thegalvanometer reading is zero. This adjustment is equivalent to makingthe first approximation in the mathematical solution of the equations(and assuming that the total extinction brought about in the sample wasdue solely to the extinction owing to the pure substance w). It will benoted that the setting of the knob w has caused adjustment ofpotentiometers wz, ws and 204 as well as of 2121 thereby making the sameassumption as to the remaining circuits as was made with respect to theone just considered.

In the next step of the procedure switch I6 is opened and switch i1closed thereby completing a circuit through the potentiometers bearingsubscripts 2 and through rheostat l I and galvanometer IS. The knob orhandle :0 is now operated until the galvometer again reads zero. Thisamounts to setting up electric potentials such that the total extinctionrepresented in potentiometer K2 is balanced out by the settings of theremaining potentiometers. It should be noted that in this as well as inthe other three circuits the battery in the circuit of potentiometer K2is poled oppositely to the batteries of the circuits of potentiometersA, B, C and D.

It may be well at this point to mention that reversing switches may beused in circuit of all the batteries in order that any negative terms inthe data may be taken care of by merely operating the correspondingswitch. The manner in which such a reversing switch is connected isshown in Figure 2 wherein a double pole double throw switch 29 has itsblades connected to opposite terminals of the battery, and its twoopposite sets of terminals connected to the fixed terminals ofpotentiometer D1 so that movement of the switch from one position to theother changes the polarity of the battery connection to thepotentiometer. Also, switches may be put in series with all of thebatteries to open the battery circuits and these switches may bemechanically interconnected so that when the device is not in use allbatteries may be open circuited.

The drawing herein illustrates the complete operation of the device ofmy invention in its simplest form. It will be obvious to those skilledin the art that without departing from my invention suitable switchesmay be provided to permit the use of the same battery in place of thebatteries i2, i3, M and I5. In a like manner, a second single batterymay supply potent-iometers A1, A2, A3 and As successively. Also a thirdsingle battery may supply potentiometers B1, B2, B3 and B4 successively,and the same is true of C1, C2, C3, C4, etc. Moreover, a singlepotentiometer may be switched successively to various positions insteadof using the series of ganged potentiometers w1, wz, 203, L04; m1, r2,m3 and :04, etc.

It will be seen that the adjustment of knob :12 has effected anadjustment of all the ac potentiometers and has thereby altered thecurrent which flows through the K1 circuit. However, the K2 circuitalthough it was modified by setting of the w handle has been adjustedsubsequently thereto, and consequently, the zero reading of thegalvanometer persists at this moment.

Now switch I! is opened, switch is closed and handle 3 adjusted untilthe galvanometer again reads zero. As before, the adjustment of the yhandle alters the setting of all potentiometers yr, 1112, ya and g4 and,consequently, the circuits in the K1 and K2 circuits would, if nowtested, no longer have zero values.

Following this switch !8 is opened, switch 19 closed and handle Cadjusted until the galvanometer again reads zero.

The operations above described are repeated until no readjustment of theadjusting handles or knobs w, r, y and z are necessary to give zeroreadings on galvanometer ill. When this occurs readings are taken fromthe scales associated with the handles w, x, y and z and these readingsgive directly (in percentage) the proportions of the constituents w, m,y and z of the original mixture.

From the above it will be seen that each variable, each constant andeach coefiicient in the equations hereinabove set forth has itselectrical counterpart in the diagram of the figure and that byinserting the values into these electrical counterparts and successivelyand repeatedly adjusting the circuits respresentative of one of the foursimultaneous equations until the galvanometer reads zero, the equationsare solved and the percentages of the constituents of the mixture arereadable directly from the dials or scales of the instrument.

It Will of course be understood that while the above description andexample has considered the analysis of a hydrocarbon mixture having fourcomponents and a device for solving equa tions resulting from suchanalysis it is entirely within the scope of this invention to extend thesystem to any number of components. For example, if a seven componentmixture were to be analyzed the system would be extended to sevencircuits each comprising a K potentiometer and seven of the coefiicientpotentiometers (such as AD) and of the associated potentiometers such asw representing the seven components of the mixture. Furthermore, as hasbeen indicated hereinabove, although the computer of my invention hasbeen described in connection with solving simultaneous equationsresulting from the analysis of hydrocarbon mixtures the system isapplicable to various types of mixtures.

Consequently, I wish to be limited not by the foregoing specification,but solely by the appended claims.

What is claimed is:

1. In a device for solving convergent systems of linear simultaneousequations, in combination, a plurality of networks each representing anequation to be solved, each network including a cell representing aconstant term, said cell including a potentiometer, a current sourceconnected in series therewith, and a reversing switch for changing thepolarity of the voltage drop pro duced across said potentiometer by thecurrent source, and a cell representing each variable term, each suchcell including a first potentiometer, a battery connected in seriestherewith, a reversing switch for changing the polarity of the voltagedrop produced across said potentiometer by said current source, and asecond potentiometer having one terminal connected to the slider of saidfirst potentiometer and its other terminal connected to a fixed terminalof said first potentiometer, leads connecting the slider of each secondpotentiometer to a fixed potentiometer terminal of the next succeedingcell, a galvanometer, a variable resistance connected in seriestherewith, a plurality of switches for connecting said galvanometer andresistor in circuit selectively with the respective networks, and meansfor simultaneously adjusting said second potentiometers by sets, eachset including one second potentiometer from each network.

2. A device for solving convergent systems of linear simultaneousequations as set forth in claim 1 in which the potentiometer of eachcell representing a constant term has a fixed resistor connected inseries therewith.

THOMAS D. MORGAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,655,276 Lichtscheindl Jan. 3,1923 1,893,009 Ward Jan. 3, 1933 2,408,081 Lovell Sept. 24, 19462,417,098 Wilcox Mar. 11, 1947 2,432,504 Boghosian Dec. 16, 1947 FOREIGNPATENTS Number Country Date 722,351 France Dec. 29, 1931

